Hello there,
This is my first post on this forum. I am hoping I chose the good section
I actually cloned the circuitry of the EQ from a Harrison 32-series console (schematics attached). It sounds very nicely but I would like to add a switch to modify the Q factors on both ranges Lo-Mid and Hi-Mid (wide to narrower bandwidth).
If anyone could have an idea of what component(s) I should play with...
Thank you !
Yann
This is my first post on this forum. I am hoping I chose the good section
I actually cloned the circuitry of the EQ from a Harrison 32-series console (schematics attached). It sounds very nicely but I would like to add a switch to modify the Q factors on both ranges Lo-Mid and Hi-Mid (wide to narrower bandwidth).
If anyone could have an idea of what component(s) I should play with...
Thank you !
Yann
Attachments
Not an expert but if you have a test bed I would monkey with R315-316 on the low mid and R349-324 on the high mid. You could try tacking a 10 k across the 2.4 k and see what that does. I think the center frequency is the C305 and C308. I think lower resistance would give lower Q, but is easier on the board than pulling the resistor out and replacing it. You'd have to do that to get a higher resisance of course. Changing the pot from 50k to 100k may also be necessary.
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R315/316 and R349/324 in series with 50k pots determine the cutoff frequencies...
Just to test for the Hi-mid I placed a resistor between pin 9 and GND of U16. I got a peak with narrower bandwidth but its gain is 20dB (standard boost/cut is 12dB). It is logical because it is a proportional Q vs Gain topology... The target is to get higher Q for the same gain...
Just to test for the Hi-mid I placed a resistor between pin 9 and GND of U16. I got a peak with narrower bandwidth but its gain is 20dB (standard boost/cut is 12dB). It is logical because it is a proportional Q vs Gain topology... The target is to get higher Q for the same gain...
Well adjust R318 & R320 to mess with the gain then to put it back where you want it. Less see, the higher the feedback resistor compared to input resistor the more gain there is, right? So tacking a 1k resistor across them to lower the gain should be an easy experiment.
If Q and gain are really inverse, then put a resistor divider to ground after the output pin 8 before the next stage. Requires lifting a pin of course. Increases noise, oh well.
If Q and gain are really inverse, then put a resistor divider to ground after the output pin 8 before the next stage. Requires lifting a pin of course. Increases noise, oh well.
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